Is it possible to create a threaded hole in wood? I'm making a kitchen island where the structure is 20mm threaded metal pipe (water pipe). I can either get flanges to connect it to the top or thread the ends of the pipe into wood. My question is around the latter option.

I see some kits online for fixing threads and rethreading however I can't find anything to drill a thread into wood of a particular size. Should be easy right?

2 Answers
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It can be done by drilling a hole just large enough to start the threaded end of the pipe in the hole. Since water pipe threads are tapered, the pipe will sort of cut threads on the way in as the pipe turns in and gets more snug as it goes in farther. I have done this, it is not the strongest connection. I don't think that finding a thread cutting tool will make it much stronger with out getting into something more elaborate, like a stepped drilled hole. Screw mounted flanges are the strongest, simplest option and can be concealed by counter sinking them into the mounting surface, or adding a skirt around the top.

You can drill a hole and force fit a threaded bar into the slightly smaller hole to force a thread, however I would only recommend this option for hard woods, if you are using chip or even ply then I would not risk it.

I see you ask about 20mm pipe, which would not have threaded inserts which you could use. The only warning I would have here is that you must have proper bracing on the bars to limit any torsion, i.e. any angular force on applied to the screw thread would easily force the rod out of the hole (at that diameter).. hence there should be three areas of bracing (end, middle, end).